The present invention relates generally to a brush holder for an electrical brush and more particularly to a brush holder with an improved spring clip arrangement.
Electrical brushes are used with various types and sizes of machinery, e.g., generators and electric motors, for collecting current from moving components. In some instances electrical brushes are employed to simply act as a pick up for the removal of static electricity which has a tendency to accumulate in moving components supported by bushings and bearings. In order to avoid integrating a brush holder into the design of an unrelated component in a piece of machinery, separate brush holders have been developed and are generally known. The primary purpose of a brush holder is to maintain contact between an electrical brush held thereby and a moving component. Replacement of brushes becomes necessary due to wear and damage, and experience has shown that a substantial amount of time can be lost because of the manner in which brushes are secured in a brush holder. As brush holder design evolved the holders changed to accommodate rapid changing of the brushes. Accordingly, the concept of designing a brush holder to accommodate changing of the brushes is also known.
Most electrical brushes are made of a carbon and graphite composition and the amount of force holding the brush against the surface of a moving component will determine the rate of brush wear as well as the rate of wear caused in the surface of the moving component. Accordingly, brush holders must accommodate replacement of the brushes in addition to providing for the application of an appropriate amount of force for biasing the electrical brush into contact with the moving component.
One commercially available approach to the above noted compound problem includes a recoil constant force spring for biasing an electrical brush toward a moving component mounted on a spring clip having multiple bends for latching the spring clip assembly in an in use position in a brush holder body. This brush holder has sufficient material to accommodate a strong spring clip assembly for biasing as well as for facilitating the changing of the brushes when the brushes and holders are of a relatively large size. However, this approach has problems with the strength and durability of spring clips which are proportionately smaller in size when brush holders of this type are relatively small. Generally stated, these spring clips have a lack of consistency in latching and remaining latched relative to the brush holder body in the in use position. This inconsistency can result in the spring clip assembly sliding or being pushed to far into the brush holder pocket to a point where it can engage and damage the moving component.
It has been found that the failure of the prior art spring clip arrangement to be positively positioned is not only related to the spring clip being weakened by being diminutive in size or because the spring clip may have become worn or damaged, but is also due to the overall faulty configuration of the spring clip arrangement. Accordingly, the most significant problem in the prior art devices was recognized as being a faulty design which resulted in the failure of the devices to positively position a spring clip in a spring clip pocket and thereby prevent the spring clip from engaging a moving component while maintaining a constant force on a brush carried in a brush holder pocket. Searching for answers to these problems resulted in the instant invention, which not only answered the above noted problems but which also provided additional improvements not previously realized.
There is a market, then, for a brush holder design, which is effective for large and small brush holders utilizing a constant force spring on a spring clip to apply constant pressure to an electrical brush guided in a brush holder pocket in the brush holder body, and which is capable of permitting the rapid interchanging of electrical brushes, especially if such a device is simple in construction and easy to use.